Crystal Illusions
by theFlyingHobbit
Summary: Big Hero 6 AU - Professor Erwin Smith has asked Eren Jaeger and his friends at the Shigansokyo Institute of Technology to help break Annie Leonhardt out of her portal-induced crystal. With this mind-boggling mystery comes the horrifying realization that there's something else going on - something that is quickly slipping out of their control.
1. Just the Beginning

**Bit of background information about this fanfiction. This story is set after the events of the movie Big Hero Six. The only things that are different is that Levi was the only one who died in the fire, and Eren is the same age as the rest of the team. There are also some other things that are different, like how I incorporated the titans, but hopefully you'll figure it out as you go.**

**This is just something I couldn't get out of my head, but here we are, with a semblance of a plot and bits and pieces of ideas. I hope you all come along for the ride.**

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><p>Eren sprinted up the stairs, barely pausing to say hello to his aunt, Armin right behind him. Disregarding the mess of papers on the floor, he leapt into a black spinny chair and turned on his computer.<p>

"Careful, don't hurt yourself," Armin said, sensors beeping.

The green-eyed boy rolled his eyes. "Calm down, Armin." He turned to poke his robot friend in the arm. "Nothing in my room is going to hurt me."

Except for the various figurines located around his room, which he constantly dropped on himself. But those didn't count.

If Armin could roll his eyes, he probably would have. Eren turned back to his computer and opened up a recent project he had been working on.

"If what Sasha told me is true," he muttered, "then with a couple tweaks here and there, this should work exactly the way I want it to…"

A couple adjustments and Eren ran the simulation. "Yes!" he shouted, kicking his legs out to propel him backwards.

"Eren? What's going on up there?" Hanji peered over the top of the stairs into his room.

"Hey, Aunt Hanji, sorry I was in such a rush, but I finally figured out that problem I was working on!" Eren said excitedly.

"Awesome," Hanji grinned. As a fellow lover of science, she was always interested in what Eren was doing.

"Dinner's ready, so you can tell me all about it."

Eren followed his aunt down the stairs, pausing to glance at a picture of his grumpy brother Levi sitting at the top of his dresser. He smiled sadly. If only Levi could see how he was doing now.

It had been a crazy two weeks after his brother died. He and his new friends from the Shigansokyo Institute of Technology had chased down a supervillain. It turned out it was Bertholdt Fubar, just a regular teenager like Eren. He wanted revenge for his sister's death...and Titan Industries was his target.

Annie Leonhardt was currently trapped in a strange crystalline shell, a byproduct of her time in what Connie called the portal-verse. They had her locked away in a sector of the Institute, for authorized personnel only. Professor Erwin Smith had informed the gang that all her vital signs were in tip-top shape though, so she was definitely alive.

"I've been working on a sort of an upgrade for Armin," Eren explained as he shoved noodles into his mouth. "It'd help him better help the injured, based on their individual chemical readings, blood type etc. Sasha was helping me because she knows more about that stuff, but I think it'll really work."

"That sounds awesome," Hanji grinned. "I guess you're really enjoying school then, huh?"

"Yeah, definitely. I regret not joining earlier," Eren replied sheepishly. He graduated high school at age 15, and the two years afterwards were spent playing video games in his garage and building random robots. He thought that was the height of intellectual activity back then, but boy was he wrong.

"I wish I could get back into a lab," Hanji said wistfully. "It's been too long since I've blown something up."

"You should come with me to the Institute sometime," Eren suggested. "Borrow one of the labs for a day. It'd be good for you."

"I am a busy, busy woman, Eren," Hanji reached across the table to ruffle his hair. "But thanks for the offer, kid, I might take you up on it someday."

-x-x-x-x-x-

"Eren! Over here!"

"Hey guys." Eren slid into the chair tiredly, dropping his backpack next to him.

"Rough class?" Mikasa asked.

"Tell me about it." Eren gratefully accepted the cookie Sasha offered. "I've never had my mind blown like that."

Jean smirked. "Welcome to the Institute. We don't just learn about science...we make science."

"Okay, check out this app I downloaded yesterday!" Sasha exclaimed.

"It was newly released today by Titan Industries," Connie added excitedly.

Jean raised an eyebrow. "Then how'd you get it yesterday?"

Sasha looked confused for a moment, then realized the problem. "Ohhhh I totally forgot to tell you guys! I got an internship at Titan Industries!"

"No way," Eren grinned.

"Nice job," Mikasa smiled.

"What?" Jean slid back in his chair. "You got the internship?"

Sasha smiled awkwardly. "Sorry, Jean, I know you really wanted it but they could only choose one..."

Jean groaned. "Beaten by the Potato Girl again…"

Sasha punched him lightly. "Don't worry, I'll distribute some top secret information, Horse Face."

Jean sighed again, but smiled slightly. "You'd better."

"Don't fear, my plasma-induced friend!" Connie declared dramatically. "I'm sure you'll find someplace that will beg for your thin apple slices."

"I know Aunt Hanji loves them," Eren joked.

"Ha-ha, very funny." Jean rolled his eyes. "Thanks for the support, guys."

"Will it make you feel better if we go back to my place?"

"Um, no. You have dirty underwear lying around."

"Not always! The maid cleans it up."

"I still can't believe you live in a mansion," Sasha muttered.

"It's part of the Springer inheritance."

"And an inheritance," Mikasa added, shaking her head.

"Okay, but Sasha has the cool lab at her house, Mikasa has the gym, Jean has the cool TV, and Eren's got the cafe. If we combined all our houses, we'd have the ultimate living area."

"Wanna fund that?" Jean snorted.

Suddenly, Armin cut in. "Your next class starts in five minutes," he said. "You should hurry."

"Thank God for this robot," Mikasa breathed, grabbing her bag. "Let's go. Sasha, get off your phone."

"Hold on, Mikasa! Someone just commented on one of my photos."

"No. We're going now."

"Hey! Ugh, fine! Gimme my phone back!"

The six of them laughed as they walked up the brick pathway to the entrance of the Institute. They only had one more class, and then Hanji had promised them cupcakes afterwards.

"Eren Jaeger?"

Eren stopped, looking around to see who was calling his name. He looked up to see Professor Erwin Smith, the esteemed founder of the Robotics program.

"Professor Erwin, what can I do for you?"

"May I speak with you and your friends for a moment?"


	2. A Timely Request

_I wonder what he wants,_ Eren wondered. Their footsteps echoed on the linoleum floors as they all awkwardly followed Erwin to wherever he was taking them.

They were all surprised when they found themselves in front of a door, reading "Authorized Personnel Only" in all caps.

"Uh, sir? Why are we here?" Mikasa asked.

Erwin didn't respond at first, placed his hand on the scanner for authentication. Then he typed in a couple things on the keypad and gestured for the others to place their hands on the scanner.

"I'll explain everything in a moment."

Jean shrugged and went to the scanner. Once they all had been scanned, the doors slid open.

"Wait," Erwin stopped Eren. "Armin can't go in."

"Why not?" Eren asked. "Whatever this is, Armin will help us a lot."

"Yes, but I'd prefer if he wasn't there unless absolutely necessary."

Eren sighed. "Fine." He turned to Armin. "Sorry, dude. You're going to have to wait out here."

"Alright," Armin responded, stepping to the side of the door.

It wasn't nearly as exciting as Eren thought it would be. No secret passageways or anything, just another hallway leading to another door.

"I'm sure you've already guessed what you're here to see," Erwin said, as he opened the door.

She looked the same as the day they found her, except now the crystal she was encased in was held up by metal supports. Connie muttered a vague Captain America reference, but Jean elbowed him.

There were also wires attached to the crystal, reading Annie's vital signs. Eren watched the steady beat of Annie's heart and wondered if she was conscious in there.

"None of our scientists have been able to get her out," Erwin began. "They can't even figure out what material the crystal is composed of. It's an extremely alien substance, and its structure seems to shift every time we try to look at it."

"Whoa...cool," Sasha breathed, walking around the exterior of the crystal. "Um...could I…?"

Erwin nodded. "I brought you here because I believe you can help. You took down the Colossal Titan, and now I want you to try and wake up his sister."

They looked at each other, not sure what they thought of Erwin's request.

Connie shrugged. "Better than going to class, in my opinion."

Erwin nodded. "Thank you. I really appreciate your service. I'll leave you to your work then."

The doors closed and Eren sighed. Connie was right, this _was_ better than going to class, but at the same time, if none of the Institute's scientists could figure it out...how would they?

"Well," Mikasa straightened her scarf. "Let's get to work."

-x-x-x-x-x-

They worked for days. They went in early to conduct a couple tests, spent the afternoon in a couple classes, and pondered the mystery at night. Hanji provided them with pastries and coffee, and sometimes Eren would walk in at 7 am to find Sasha already staring at the crystalline structure. Turns out she had been there for hours.

Even so...Annie Leonhardt kept her secrets.

"It just doesn't make any sense!" Sasha threw her hands up in the air, pacing around the room madly. "I've test every element there is, but none of them form this way."

"Well, it _is_ an alien substance," Connie pointed out, chewing on a donut.

"I know! So basically, we're trying to discover a new element."

"It's harder than anything I've ever seen," Jean said. He had brought in his gear one day to see if they could cut Annie out, or at least a sample so Sasha could test it more easily. "I couldn't even make a scratch."

"No magnetic properties either," Mikasa added.

"Extremely resistant to heat." Connie pitched in. "The thing stayed like an iceberg when I heated it up."

"You tried to heat it up?!" Jean screeched. "You realize that could have been dangerous for her, right?"

Connie waved his donut in the air nonchalantly. "Relax. Her vital signs never changed."

Eren groaned. "I don't know how to solve this either, guys."

"Do you think Armin could help?" Mikasa wondered.

"Armin only knows things that he's programmed to know," Eren sighed. "We don't know what it is, so Armin definitely can't."

"No, I agree with Mikasa," Jean cut in. "There must be something we're missing. Maybe Armin could scan the crystal and maybe detect something we can't."

"Professor Erwin's been pretty tough about not letting Armin in here though," Eren reminded.

"Talk to him about it," Sasha said. "I'm sure he'll understand if we explain the situation to him."

Eren shrugged. "It's worth a try, I guess."

They picked up Armin from outside and made their way down the hallway to Professor Erwin's office.

"Professor Erwin?"

Erwin looked up as the six walked into the room. "Oh, hello. What can I do for you?"

They had decided that Mikasa should be the designated speech-maker. "We haven't been able to make much progress with Annie. We've tested the crystal and even tried to cut her out forcibly but nothing works. We were wondering if we could have your permission to bring Armin in. We think that he could scan the crystal, maybe pick up on something that we missed."

"I would prefer if you didn't," Erwin said.

Mikasa hesitated. "I thought you wanted us to get Annie out of the crystal. We're trying everything we can think of."

"Armin will retain the memory of being in the chamber. This is a top secret assignment, and if word gets out that we're facilitating a person in the Institute, it won't end well," Erwin explained.

Eren opened his mouth to say something but Erwin stopped him. "It's not up for discussion."

They were forced to leave. As soon as the door closed behind them, Eren groaned.

"It just doesn't make sense!" he complained. "Professor Erwin's logic doesn't even make sense. I can delete the memory from Armin's chip, it's an easy push of the button."

"Maybe he doesn't want to take the chance that something could happen," Jean suggested.

"Yeah," Eren sighed. "But he trusts us enough to ask us to help with this...wouldn't he trust us with this one little thing."

"You're right, Eren," Mikasa's eyes were narrowed in thought. "There's something weird going on here."

"Then what do we do?"


End file.
